Gas burner pilot control



Feb. 24, 1970 w. 1'. KEMP EI'AL GAS BURNER PILOT CONTROL 2 Sheets-Sheet 1 Filed Oct. 1, 1968 INVENTORS 7. KEMP WAYNE JOSEPH E BUCZEWSK/ EDW 0M. REDSTREA E, JR.

United States Patent O M 3,496,926 GAS BURNER PILOT CONTROL Wayne T. Kemp, Kutztown, and Joseph F. Buczewski and Edward M. Retlstreake, Jr., Macungie, Pa., assignors to Caloric Corporation, Topton, Pa., a corporation of Pennsylvania Filed Oct. 1, 1968, Ser. No. 764,182 Int. Cl. F24c 3/10 U.S. Cl. 126-39 5 Claims ABSTRACT OF THE DISCLOSURE In a gas-fueled oven, a system for supplying fresh air to the flame of a pilot which is subjected to contaminated air, and for preventing the flame from being extinguished by sudden changes in air pressure caused by opening and closing the oven door. The system comprises a snorkel which is connected at one end to the pilot burner and has its opposite end disposed outside the oven compartment for supplying fresh primary air to the pilot flame, and means intermediate the ends of the snorkel and communicating with the oven compartment for balancing air pres sure in the snorkel between the pilot and the communieating means for preventing accidental extinction of the pilot flame.

BACKGROUND OF THE INVENTION This invention relates to a pilot burner system for gasfueled ovens and has particular reference to a pilot burner which is located in an area subjected to contaminated air and which further is normally subject to flame extinction by sudden changes in air pressure within an oven such as might be caused by opening and closing the oven door.

A pilot burner must be located closely adjacent an oven burner so that its flame, which burns constantly, will ignite the oven burner when fuel is supplied to the burner. However, when the pilot flame is enveloped in contaminated air or combustion products, it will become extinguished unless a supply of fresh air is provided. This is particularly true of the pilot flame for the upper or broil burner in a two-burner, single-compartment oven when the contaminated air and combustion products produced by the lower or bake burner envelope the pilot flame. Such a pilot flame is also subject to extinction upon the quick opening or closing of the oven door which creates sudden changes in air pressure within the oven.

Heretofore, attempts have been made to overcome these problems by attaching one end of a snorkel or tube to the pilotburner with the other end of the snorkel being disposed within the oven at or below the level of the bottom burner to convey supposedly uncontaminated air to the pilot flame. This has been found to provide great improvement in the operation of the pilot burner. However, it also has been found that some of the contaminated air in the oven may be drawn by inspiration into the snorkel. This may be caused, for example, by improper functioning of the flue exhaust system and causes resultant buildup of contaminated air and combustion products in the oven compartment.

The problem of extinction of the pilot flame by sudden thanges in air pressure within the oven has been partially overcome by locating the open lower end of the snorkel within the oven compartment so that air pressure at this lower end will be balanced with respect to the air pressure at the pilot flame. Thus, opening and closing of the oven door will not cause a change in the air pressure at the pilot burner such as will extinguish the pilot flame. However, a baffle box or other means built around the open end of the snorkel has been required in order to ensure the desired flow of oven air into the open end of the snorkel when air pressure is increased in the oven 3,496,926 Patented Feb. 24, 1970 such as by the closing of the oven door, and to retain air pressure balance at the ends of the snorkel when the door is opened. However, the use of such means, particularly when the box is provided with a series of baflles, presents added complications and expense to oven manufacture.

SUMMARY OF THE INVENTION The above and other disadvantages of the prior art are overcome by the present invention in which there is provided an oven having a pilot burner which may be located, during use of the oven, in an area of contaminated air and/or combustion products created by an oven burner. In accordance with this invention, the pilot burner is provided, through a snorkel, with fresh primary air from a source outside the oven compartment whereby the air supplied to the pilot flame will at all times be fresh and uncontaminated regardless of the amount of contaminated air and combusion products which is present in the oven. Also, according to this invention, there is provided novel means for maintaining a balance between the air pressure at the pilot burner end of the snorkel and at a point along the snorkel which is remote from the pilot burner whereby extinction of the pilot flame by changes in air pressure in the oven is prevented. This last-mentioned feature is achieved by extending the snorkel partially within a wall of the oven. The exposed portion of the snorkel is provided with a series of small openings located opposite the wall opening and through which air within the lower portion of the oven beneath the level of the bottom burner passes into the snorkel when the air pressure in the oven is increased as by closing the oven door. This will create a balance of air pressure in the snorkel so that such changes in air pressure will not extinguish the pilot flame. Likewise, such a balance in air pressure is achieved when the air pressure in the oven is decreased as by opening the door. In the normal operation of the pilot burner, the exposed portion of the snorkel within the box is heated when the oven burner is operating. This warms the uncontaminated air within the tube, causing it to rise, and assisting in inspiration of clean primary air from outside the oven compartment through the end of the snorkel.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of this invention will become more apparent from the following description taken in connection with the accompanying drawings, wherein:

FIG. 1 is a front elevational view of a gas-fueled oven embodying a pilot burner system embodying the present invention, the oven being shown with fragmentary front panel and with the oven door removed; and

FIG. 2 is a side elevational view, partly in section, of the oven shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings wherein like characters of reference designate like parts throughout the several views, there is shown in FIG. 1 a household gas range which includes an oven having therein a system embodying this invention. The range is shown without the top burners and gas supply connections thereto which do not in themselves constitute any part of this invention. Likewise, details of the controls for the top burners have also been omitted from the drawings, as well as details of the controls for the oven burners, since such controls in themselves also constitute no part of the present invention.

More particularly, the range comprises an upstanding, substantially box-like, metal body 12 carrying a substantially horizontal metal cooking top 14 and upstanding metal backsplash 16 and side splashes 18 arranged respectively at the back and sides of the cooking top 14'.

3 Within the body 12 is a substantially box-shaped metal liner which defines an oven cooking cavity 22 and comprises a rear wall 24, a top wall 26, a bottom wall 28 and a pair of side walls 29. The interior surfaces of-the liner 20 may be finished in any conventional manner such as, for example, by carrying a layer of porcelain enamel of the glass frit type. An opening is provided in the front of the range and through the liner front wall 30, whereby the interior of the oven cooking cavity 22 is accessible from the front of the body. A door 32 (FIG. 2) is mounted upon the front of the body 12 by any suitable hinge structure whereby the door is pivotally movable into open or closed relation with respect to the open front of the cavity 22. The door hinge, handle and latching structures are not shown and do not in themselves constitute part of the present invention. 1

The liner top wall 26 is spaced well below the cooking top 14 and heat insulated therefrom by a bolt 34 of fibrous glass or other selected insulating material which is intended to aid in confining heat as much as possible to the interior of the cavity 22 during operation of the oven. The door 32 may be similarly filled with insulating material 36, and at the back of the range an insulating rear wall or shield 38 is provided in spaced relation with the oven rear wall 24, and the space therebetween is also filled with insulation 40. As shown in FIG. 1, the outer side walls of the range are similarly insulated from the side walls 29 of the oven liner by insulating material 41. Thus, the top, sides, rear and front of the oven are completely insulated from adjacent portions of the range and from the exterior atmosphere. The bottom wall 28 of the oven cavity may comprise a heat reflecting shield or plate which may be also insulative in function to protect the floor beneath the range.

Within the oven cavity 22 there is provided a lower burner 44 which is located in the lower extremity of the oven cavity 22 beneath a partition 46 which is supported in any suitable manner by the back or side walls of the liner and is suitably spaced therefrom at points throughout its periphery or is provided with openings 47 so that the oven liner actually comprises a single cavity or compartment. The partition 46 merely serves as a means for distributing oven burner flue products within the compartment and is out of physical engagement with the lower burner 44. Burner 44 extends a substantial distance across the width of the cavity 22 and may be of a conventional blue-flame type comprising a ported burner head 48 having a gas receiving chamber for receiving gaseous fuel from a venturi 50 or the like which is suitably mounted to receive gas from a supply line 52 and to admix the gas with air in the conventional and well-known manner. A constantly burning pilot light 54 is suitably connected into the gas supply system and is located adjacent the burner head 48 so that jets of flame will be ignited at each of the ports in the head when the control system (not shown) is operated to allow gas to flow into the head.

The lower burner 44 is located beneath partition 46 and is enclosed on the bottom and sides by a heat reflecting shield 56 which functions to deflect heat upwardly through the compartment or cavity 22. Suitable vents may be provided in the bottom Wall 28 and shield 56 to insure that suflicient air enters the cavity to sustain combustion of gas at burner 44.

In the oven compartment at the upper extremity thereof is a burner 64 which may be of a type which produces a broad sheet of flame or incandescence. The burner 64 includes a burner head 66 and a mixing chamber such as a venturi 68 which enables communication between the burner head and a gas supply pipe 72, in the wellknown manner. Pipe 72 is connected to the supply line 52 and is also connected into the control system (not shown) so that when the control system is operated to allow gas to flow from pipe 72 into the mixing chamber 68, where it becomes mixed with air, and then into burner head 66, it will become ignited by a constantly burning flame of a pilot burner 78 located adjacent the burner 64. This creates a broad flame which radiates energy throughout the oven cavity. The upper burner 64 is normally used for broiling operations, while the lower burner 44 is normally used for baking purposes.

It will be noted that primary air is provided for the upper burner head 64 by means of a duct 80 which extends upwardly along the rear wall 24 and terminates at its upper end at an opening 81 through the rear wall into which the mixing chamber 68 or venturi extends. Since the lower end of the duct 80 terminates in the lower regions of the range outside of the oven compartment 22, a constant supply of uncontaminated air is allowed to pass into the burner head 64. The lower end of duct 80 may be terminated in any suitable manner so that this is achieved.

It will be understood that the burners 44 and 64 may be operated individually and separately from one another for conventional baking and broiling operations. However, both burners are operated simultaneously for performing a self-cleaning operation. In the heat cleaning cycle, ambient air is swept upwardly through the oven cavity and through an exit or exhaust opening 86 (FIG. 1) into a flue or duct 88 (FIG. 2) from which it flows out of openings 90 in the front of the backsplash 16. This flow of air is intended to carry with it the gaseous degradation products resulting from the pyrolysis of food soils during a self-cleaning cycle. The lower end of the flue 88 communicates directly with the fresh air supply beneath or at the rear of the oven cavity, and it will be apparent that a flow of fresh air will be constantly maintained because of the tendency of heated air to rise.

However, a serious problem exists in that the upper pilot burner flame is enveloped in contaminated air or combustion products when the lower burner 44 is operated. This will cause the upper pilot flame to become extinguished unless a supply of fresh air is provided. The upper pilot flame is also subject to extinction when the air pressure within the oven cavity is suddenly changed, such as occurs upon the quick opening or closing of the oven door.

A supply of fresh primary air is provided at upper pilot burner 78 by snorkel which has one end connected directly to the burner 78 and which extends therefrom into a side wall of the oven and then downwardly through the wall to a supply of fresh uncontaminated air beneath the range. This is clearly illustrated in FIG. 1 wherein it will be seen that the lower end 102 of the snorkel 100 extends into the open air beneath the bottom wall 28 of the oven compartment. Thus, the air supplied to the upper pilot flame will at all times be fresh air uncontaminated, regardless of the amount of contaminated air and combustion products which is present in the oven.

Means is further provided for maintaining a balance between the air pressure at the upper end of the snorkel and at a lower point along the length of the snorkel remote from the upper pilot burner whereby extinction of the upper pilot flame by changes in air pressure in the oven is prevented. This is achieved by providing an opening 104 in the inner wall 29 of the oven in its lower extremity, at or below the level of the lower burner 44, through which opening a relatively small portion of the snorkel is exposed to the atmosphere within this lower portion of the oven. To accomplish this, the opening is provided with a box 106 which extends into the insulation 41 and through which the snorkel vertically extends, as shown clearly in FIG. 1. The snorkel is provided with a series of openings 108 which function to aid in maintaining a constant air pressure in the snorkel between the upper pilot burner 78 and the portion thereof disposed within box 108, as will be described below. Thus, air pressure changes within the cavity, which may occur upon sudden opening or closing of the oven door, will not cause the upper pilot flame to become extinguished. For example, when the oven door is suddenly closed, this will cause air pressure within the oven to increase in the upper pilot burner 78. However, air pressure will also increase within the lower portion of the snorkel 100 by virtue of the fact that air will be forced simultaneously into the snorkel through openings 108. Likewise, sudden decreases in air pressure are similarly compensated for by utilization of the exposed portion of the snorkel together with openings 108 communicating with the lower regions of the oven cavity.

It will be apparent that the objectives of this invention have been achieved by the device shown and described. However, it is to be understood that certain modifications in the invention may be made by those skilled in the art without departing from the spirit of the invention as expressed in the accompanying claims.

What is claimed is:

1. A gas oven structure comprising a cooking compartment having therein upper and lower gas-fueled main burners, a pilot burner for said upper main burner, first means for supplying said pilot burner with fresh primary air from a source external to said compartment, said means comprising a snorkel tube having an outlet end connected to the pilot burner and an inlet end disposed outside the compartment, and second means intermediate the ends of said tube and communicating with the interior of said compartment for balancing air pressure at said pilot burner during changes in air pressure within the compartment.

2. A gas oven structure as set forth in claim 1 wherein said snorkel tube extends throughout a substantial portion of its length within a wall of the oven, and said second means comprises an apertured portion of the tube which is exposed to the interior of said compartment.

3. A gas oven structure as set forth in claim 2 wherein said apertured portion of the tube is exposed to the interior of the compartment at a level which is at or below the level of the lower main burner.

4. A gas oven structure as set forth in claim 2 wherein said wall of the oven is provided with an opening disposed at or below the level of the lower main burner, a box is mounted within said wall over said opening and has an opening therein aligned with the opening in the wall, and the apertured portion of the tube extends Within said box whereby air pressure within the tube is balanced with respect to air pressure at the pilot burner.

5. A gas oven structure comprising a cooking compartment having therein upper and lower gas-fueled main burners, a pilot burner for said upper main burner, a snorkel tube having on end connected to the pilot burner and having its opposite end disposed outside the compartment within a source of fresh uncontaminated primary air to be supplied to said pilot burner, and means for subjecting a portion of the interior of said tube intermediate its ends to heat directly from within the compartment for assisting in inspiration of said primary air from outside the compartment to the pilot burner.

References Cited UNITED STATES PATENTS 3,114,363 12/1963 Koltun 126-41 3,320,943 5/1967 Crannell et al.

3,338,231 8/1967 Lamar.

3,376,862 4/1968 Riehl.

3,422,810 1/1969 Weiss 12641 CHARLES J. MYHRE, Primary Examiner 

